Electrophotographic photosensitive member

ABSTRACT

An electrophotographic photosensitive member has a photosensitive layer on an electroconductive support. The photosensitive layer comprises a compound having a structure represented by the general formula (1) or (2) as a charge-generating material: ##STR1## wherein A 1  and A 3  are respectively an alkyl radical, an aralkyl radical, an aromatic radical or a heterocyclic radical which may have a substituent; A 2  is hydrogen atom, or an alkyl radical, an aralkyl radical, an aromatic radical, or a heterocyclic radical which may have a substituent; A 1  and A 2  may be the same with or different from each other; A 1  and A 2  may be linked together to form a ring; and n is an integer of 1, 2, or 3.

This application is a continuation of application Ser. No. 07/766,976filed Sept. 26, 1991, now abandoned, which is a continuation ofapplication Ser. No. 07/488,732 filed Feb. 26, 1990, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrophotographic photosensitivemember. More particularly, the present invention relates to anelectrophotographic photosensitive member superior in sensitivity andpotential stability.

2. Related Background Art

Recent electrophotographic photosensitive members comprising an organiccompound as a main constituent have various advantages such as superiorfilm-forming property, non-pollution, ease of manufacture, and so on, ascompared with inorganic type photosensitive members. In particular, somelamination type photosensitive members are practically used whichincludes a layer containing a material for generating electric charge onlight irradiation (a charge-generating layer and a layer containing amaterial for transporting the generated charge (a charge-transportinglayer) because of their higher sensitivity and high-charge stability.Photosensitive members employing an azo pigment which is a typicalcharge-generating material were disclosed in Japanese Patent ApplicationLaid-open No. 59-33445 and No. 60-111249. Such photosensitive membersemploying the azo pigment as the charge-generating material are notalways satisfactory in sensitivity, residual potential, or stability inrepeated use, and are limited in the range of selection of thecharge-transporting material, thus not satisfying extensive requirementsfor electrophotographic processes.

SUMMARY OF THE INVENTION

The present invention intends to provide an electrophotographicphotosensitive member having a high sensitivity and high durability.

The present invention provides an electrophotographic photosensitivemember having a photosensitive layer on an electroconductive support,the photosensitive layer comprising a compound represented by thegeneral formula (1) or (2) as a charge-generating material: ##STR2##wherein A₁ and A₃ are respectively an alkyl radical, an aralkyl radical,an aromatic radical or a heterocyclic radical which may have asubstituent; A₂ is hydrogen atom, or an alkyl radical, an aralkylradical, an aromatic radical, or a heterocyclic radical which may have asubstituent; A₁ and A₂ may be the same with or different from eachother; A₁ and A₂ may be linked together to form a ring; and n is aninteger of 1, 2, or 3.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates an example of constitution of a usual transfer-typeelectrophotographic photosensitive member employing a drum-formphotosensitive member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For the radicals of A₁, A₂, and A₃ in the present invention, the alkylradicals include methyl, ethyl, propyl, butyl, etc. The aralkyl radicalstherefor include benzyl, phenethyl, naphthylmethyl, etc. The aromaticradicals therefor include aromatic monocyclic radicals and aromaticcondensed polycyclic radicals of compounds such as benzene, naphthalene,anthracene, phenanthrene, pyrene, azulene, indene, fluorene, etc.;assembled ring radicals constituted by direct combination through adouble bond or the like of two or more of the aforementioned aromaticmonocyclic groups and aromatic condensed polycyclic radicals; aromaticketone radicals such as benzophenone, fluorenone, benzanethrone,indanone, suberenone, etc., their sulfur derivative radicals (e.g.,thiobenzophenone), and their dicyanomethylene derivative radicals; andaromatic quinone radicals of compounds such as benzoquinone,naphthoquinone, anthraquinone, phenanthrenequinone, pyrenequinone, etc.,their sulfur derivative radicals, and their dicyanomethylene derivativeradicals. The heterocyclic radicals therefor include heterocyclicmonocyclic ring radicals and heterocyclic radicals condensed with abenzene ring or an aromatic condensed polycyclic group of a compoundsuch as furan, thiophene, pyrrole, oxazole, thiazole, imidazole,pyrazole, pyridine, pyrazine, piperadine, benzofuran, benzothiophene,indole, benzoxazole, benzothiazole, dibenzofuran, dibenzothiophene,carbazole, phenazine, phenoxazine, phenothiazine, thianthrene, acridone,etc.; and assembled ring radicals constituted by direct combinationthrough a double bond or the like of two or more of the aforementionedaromatic monocyclic and condensed polycyclic radicals. The assembledring radicals may be constituted by direct combination of at least oneof the heterocyclic monocyclic radicals and condensed heterocyclicradicals and at least one of the aromatic monocyclic radicals andaromatic condensed polycyclic radicals.

The substituents which may be attached to the alkyl radicals, thearalkyl radicals, or the heterocyclic radicals mentioned above includehalogen substituents such as fluorine, chlorine, bromine, and iodine;alkyl radicals such as methyl, ethyl, propyl, butyl, etc.; alkoxyradicals such as methoxy, ethoxy, phenoxy, etc.; a nitro radical; acyano radical: substituted amino radicals such as dimethylamino,dimethylamino, diphenylamino, dibenzylamino, morpholino, piperidino,pyrrolidino, etc.

In the general formulas (1) and (2), A₁ and A₂ may be the same with ordifferent from each other, A₁ and A₂ may be linked together to form aring, and n is an integer of 1, 2, or 3. Moreover, in the generalformulas (1) and (2). when A₁ and A₂ are electron-donating moieties. A₃is preferably an electron-accepting moiety, and when A₁ and A₂ areelectron-accepting moieties, then A₃ is preferably an electron-donatingmoiety. In particular, excellent characteristics are achieved in thecase where an electron-donating moiety is linked on the N side ofthe >C═N-- bond, and an electron-accepting moiety is linked on the Cside thereof.

The electron-donating moiety includes aromatic monocyclic radicals andaromatic condensed polycyclic radicals of compounds such as benzene,naphthalene, anthracene, phenanthrene, indene, fluorene, etc. which havean electron-donating substituent, and pyrene etc. which may have anelectron-donating substituent; electron-donating aromatic amine radicalsof compounds such as triphenylamine, diphenylamine, diphenylmethylamine,etc. which may have an electron-donating substituent; electron-donatingheterocyclic monocyclic radicals and electron-donating condensedheterocyclic radicals which are constituted by condensation with abenzene ring or an aromatic condensed polycyclic group of a compoundsuch as furan, thiophene, pyrrole, oxazole, thiazole, imidazole,pyridine, pyrazine, acridine, phenazine, benzofuran, benzothiophene,dibenzofuran, dibenzothiophene, benzoxazole, benzothiazole, thianthrene,phenoxazine, phenothiazine, etc. which have an electron-donatingsubstituent, and radicals of indole, carbazole, iminodibenzyl,tetrathiafulvalene, dibenzotetrathiafluvalene, etc. which may have anelectron-donating substituent; and assembled ring radicals constitutedby direct combination through a double bond or the like of two or moreof the aforementioned monocyclic groups and condensed polycylicradicals.

The electron-donating substituent includes alkyl radicals such asmethyl, ethyl, propyl, butyl, etc.; aryl radicals such as phenyl,naphthyl, etc.; aralkyl radicals such as benzyl, phenethyl, etc; alkoxyradicals such as methoxy, ethoxy, etc.: and substituted amino radicalssuch as dimethylamino, diphenylamino, morpholino, etc.

On the other hand, the electron-accepting moiety includeelectron-accepting aromatic monocyclic radicals and electron-acceptingaromatic condensed polycyclic radicals of such as benzene, naphthalene,anthracene, phenanthrene, indene, fluorene, etc. which have anelectron-accepting substituent; electron-accepting aromatic ketoneradicals of such as benzophenone, fluorenone, benzanthrone, etc. whichmay have an electron-accepting substituent, and their dicyanomethylenederivative radicals; electron-accepting aromatic thioketone radicals;electron-accepting aromatic quinone radicals of compounds such asbenzoquinone, naphthoquinone, anthraquinone, pyrenequinone, etc., andtheir dicyanomethylene derivative radicals; electron-acceptingheterocyclic monocyclic radicals and electron-accepting condensedheterocyclic radicals which are constituted by condensation with abenzene ring or an aromatic condensed polycyclic group of a compoundsuch as furan, thiophene, pyrrole, oxazole, thiazole, imidazole,pyridine, pyrazine, acridine, phenazine, benzofuran, benzothiophene,dibenzofuran, dibenzothiophene, benzoxazole, benzothiazole, thianthrene,phenoxazine, phenothiazine, etc. which have an electron-acceptingsubstituent; and electron-accepting assembled ring radicals constitutedby direct combination through a double bond or the like of two or moreof the aforementioned aromatic monocyclic or condensed polycyclicradicals.

The electron-accepting substituent includes halogens such as fluorine,chlorine, bromine, and iodine a nitro radical: and a cyano radical.

In the present invention, the term "electron-donating radical" and"electron-accepting radical" mean a moiety exhibiting a negative valueof Hammet's σ constant, and a moiety exhibiting a positive value ofHammet's σ constant, respectively.

As A₂, hydrogen is especially preferable from among the above-mentionedradicals.

In order to achieve spectrographic sensitivity of electrophotographicphotosensitive member in a long wavelength region, the charge-generatingmaterial is required to exhibit absorption spectrum at the longwavelength region. Extension of a π-electron conjugation system, orincrease of intermolecular interaction are known to give long-wavelengthabsorption. As to the substituent effect, it has been reported thatsubstituted azobenzenes have stronger absorption at long wavelengths asthe substituent has stronger electron-donating property, or as thesubstituent has a stronger electron-accepting property. This effect isconsidered to result from the intermolecular charge-transfer interactionthrough the azo group (--N═N--), namely a π-electron conjugation chain,of the azobenzene (J.Griffiths, "Colour and Construction of OrganicMolecules", Academic Press London, 1976, and great increase of longwavelength absorption is expected to be given by combination of a strongelectron-donating moiety and a strong electron-accepting moiety.

On the other hand, the improvement of charge carrier generationefficiency is required for improving sensitivity in electrophotographicphotosensitive members. One factor relating to the charge carriergeneration efficiency is a dissociation efficiency of the carrier. Alocal electric field, which is formed by ionically adsorbed gas or thelike, is reported to have a great influence on the carrier dissociationefficiency in the case of phthalocyanine compounds (see, for example,Denki Shashin Gakkaishi (Journal of Electrophotographic Society) Vol.20,p.216, (1987)).

From the standpoint as described above, the photoconductive compounds ofthe present invention exhibits excellent characteristics, in particularin the case where the electron-donating moiety and theelectron-accepting moiety interact mutually through the >C═N-- bond, andfurther the electron-donating moiety and the electron-accepting moietyinteract mutually between molecules in a crystalline state to causecharge transfer.

Typical examples of the compounds represented by the general formulas(1) and (2) are shown below.

    __________________________________________________________________________     ##STR3##                                                    (1)              Com-                                                                          pound                                                                         No.  Structural formula                                                       __________________________________________________________________________     A-1                                                                                ##STR4##                                                                 A-2                                                                                ##STR5##                                                                 A-3                                                                                ##STR6##                                                                 A-4                                                                                ##STR7##                                                                 A-5                                                                                ##STR8##                                                                 A-6                                                                                ##STR9##                                                                 A-7                                                                                ##STR10##                                                                A-8                                                                                ##STR11##                                                                A-9                                                                                ##STR12##                                                               A-10                                                                                ##STR13##                                                               A-11                                                                                ##STR14##                                                               A-12                                                                                ##STR15##                                                               A-13                                                                                ##STR16##                                                               A-14                                                                                ##STR17##                                                               A-15                                                                                ##STR18##                                                               A-16                                                                                ##STR19##                                                               A-17                                                                                ##STR20##                                                               A-18                                                                                ##STR21##                                                               A-19                                                                                ##STR22##                                                               A-20                                                                                ##STR23##                                                               A-21                                                                                ##STR24##                                                               __________________________________________________________________________

      ##STR25##      (2)      Compound No. Structural formula     B-1      ##STR26##      B-2     ##STR27##      B-3     ##STR28##      B-4     ##STR29##      B-5     ##STR30##      B-6     ##STR31##      B-7     ##STR32##      B-8     ##STR33##      B-9     ##STR34##      B-10     ##STR35##      B-11     ##STR36##      B-12     ##STR37##      B-13     ##STR38##      B-14     ##STR39##      B-15     ##STR40##      B-16     ##STR41##      B-17     ##STR42##      B-18     ##STR43##      B-19     ##STR44##      B-20     ##STR45##      B-21     ##STR46##      B-22     ##STR47##      B-23     ##STR48##      B-24     ##STR49##      B-25     ##STR50##      B-26     ##STR51##      B-27     ##STR52##      B-28     ##STR53##

The compounds represented by the general formulas (1) and (2) aresynthesized readily by the dehydrating-condensation reaction of acorresponding aromatic amine and an aromatic aldehyde or an aromaticketone in the presence of a basic catalyst as shown in the reactionformula below.

Acid or base

    Ar--CHO+Ar'--NH.sub.2 →Ar--CH═N--Ar'

The electrophotographic photosensitive member of the present inventionis provided on an electroconductive support& with a photosensitive layercontaining the compound represented by the general formula (1) or (2) asthe charge-generating material.

The photosensitive layer may be in any form. A function-separating typeof photosensitive layer is particularly preferable which is constitutedof a charge-generating layer containing the compound represented by thegeneral formula (1) or (2), and a charge-transporting layer containing acharge-transporting material laminated thereon.

In this case, the charge-generating layer is formed by applying on anelectroconductive supporter a coating solution containing a binder resindispersed in a suitable solvent by a known method. The film is desirablymade thin, for example, to a thickness of 5 μm or less, preferably from0.01 μm to 1 μm.

The binder resin employed therefor may be selected from broad range ofinsulative resins and organic photoconductive resins. The preferableresins include polyvinyl butyrals, polyvinyl benzals, polyarylates,polycarbonates, polyesters, phenoxy resins, cellulose resins, acrylicresins, urethane resins, etc. The content thereof in thecharge-generating layer is not more than 80% by weight, preferably notmore than 40% by weight.

The solvent for the binder resin is preferably selected from solventswhich dissolve the aforementioned resin but do not dissolve thecharge-transporting layer or the subbing layer mentioned below.Specifically the solvent includes ethers such as tetrahydrofuran,1,4-dioxane, etc.; ketones such as cyclohexanone, methyl ethyl ketone,etc.; amides such as N,N-dimethylformamide, etc.; esters such as methylacetate, ethyl acetate, etc.; aromatic solvents such as toluene, xylene,monochlorobenzene, etc.; alcohols such as methanol, ethanol, 2-propanol,etc.; and aliphatic haIogenated hydrocarbons such as chloroform,methylene chloride, etc.

The charge-transporting layer, which is laminated on the upper side orthe lower side of the charge-generating layer, functions to receivecharge carriers from the charge-generating layer in an electric field,and transport the carriers to the surface. The charge-transporting layeris formed by applying a charge-transporting material, with a suitablebinder if necessary, dissolved in a solvent Generally the thickness ofth®film is preferably in the range of from 5 μm to 40 μm, morepreferably from 15 μm to 30 μm.

The charge-transporting material includes electron-transportingmaterials and positive-hole-transporting materials. Examples of theelectron-transporting materials are electron-attracting materials suchas 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone. chloranil,tetracyanoquinodimethane, etc. and polymerized products of theseelectron-attracting materials.

The examples of the positive-hole-transporting materials are aromaticpolycyclic compounds such as pyrene, anthracenne, etc.; heterocycliccompounds such as carbazole, indole, imidazole, oxazole, thiazole,oxadiazole, pyrazole, pyrazoline, thiadiazole, triazole, etc.; hydrazonecompounds such as p-diethylaminobenzaldehyde-N,N-diphenylhydrazone,N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, etc.; styrylcompounds such as α-phenyl-4'-N,N-diphenylaminostylbene,5-[4-(di-ptolylamino)benzylidene]-5H-dibenzo[a,d]cycloheptene, etc.;benzidine compounds; triarylmethane compounds triphenyl amines; polymerssuch as poly-N-vinylcarbazole, polyvinylanthracene, etc. having in themain chain or a side chain radicals from the aforementioned compounds.

Inorganic materials such as selenium, selenium-tellurium, amorphoussilicon, etc. may also be used in addition to the organiccharge-transporting materials.

The above-mentioned charge-transporting materials may be used singly orin combination of two or more materials.

When a charge-transporting material having no film-forming property isused, a suitable binder may be used with it. Specific examples of thebinders includes insulative resins such as acrylic resins, polyarylates,polyesters, polycarbonates, polystyrenes, acrylnitrile-styrenecopolymers, polysulfones, polyacrylamides, polyamides, chlorinatedrubbers, etc.; organic photoconductive polymers such aspoly-N-vinylcarbazole, polyvinylanthracene, etc; and the like.

Useful materials for the electroconductive support include aluminum,aluminum alloys, copper, zinc, stainless steel, titanium, etc. Inaddition thereto, also useful are plastics coated with a film of thesemetals formed by vacuum vapor deposition; plastic or metal supporterscoated with electroconductive particles (e.g., carbon black, silverparticles etc.) together with a binder; plastics or paper impregnatedwith electroconductive particles; and the like.

The electroconductive support may either be in a form of sheet or in aform of a drum.

Between the electroconductive supporter and the photosensitive layer, asubbing layer may be provided which has a barrier function and anadhesion function. The subbing layer may have a thickness of 5 μm orless, preferably from 0.1 μm to 3 μm. The subbing layer may be formedfrom a material such as casein, polyvinyl alcohol, nitrocellulose,polyamides (nylon 6, nylon 66, nylon 610, copolymer nylon,N-alkoxymethylated nylon, etc), polyurethane, aluminum oxide, etc.

On the photosensitive layer, there may be laminated a resin layer, or aresin layer containing electroconductive material dispersed therein, asa protecting layer.

Another specific example of the present invention is aneleotrophotographic photosensitive member containing the above-mentionedcompound and a charge transporting material in the same layer. In thisexample, a charge transfer complex composed of poly-N-vinylcarbazole andtrinitrofluorenone may be used as the charge transporting material.

The electrophotographic photosensitive member of this example may beformed by applying a liquid comprising the above-mentioned compound andthe charge transporting material dispersed in a suitable resin solution,and drying it.

In any of the electrophotographic photosensitive members, the employedcompound represented by the general formula (1) or (2) may either becrystalline or non-crystalline, and may be employed in combination oftwo or more compounds represented by the general formula (1) or (2), orin combination with a known charge-generating material.

The electrophotographic photosensitive member of the present inventionis useful not only for electrophotographic copying machines but is alsowidely useful in electrophotography application field such as laser beamprinters, CRT printers, LED printers, liquid crystal printers, laserengraving, etc.

FIG. 1 illustrates an outline of constitution of a usual transfer-typeelectrophotographic photosensitive member employing a photosensitivemember in a drum form.

In the figure, the numeral 1 denotes a drum type photosensitive memberas an image bearer, which is driven to rotate around the axis 1a in thearrow direction at a predetermined peripheral speed. The photosensitivemember 1 is electrostatically charged uniformly to a predeterminedpositive or negative potential at the peripheral surface with a chargingmeans 2 while rotating. Then it is exposed to an image-projecting lightL (e.g., slit projection, laser beam scanning projection, etc.) at thelight exposure portion 3 from an image-projecting means not shown in thefigure. Thus an electrostatic latent image is successively formed on theperipheral surface of the photosensitive member.

The electrostatic latent image is subsequently developed by use of atoner with the image-developing means 4. The developed toner image issequentially transferred by a transfer means 5 onto thetransfer-receiving medium P which is fed from a paper feed section (no&shown) between the photosensitive member 1 and the transfer means 5synchronously with the rotation of the photosensitive member 1.

The transfer-receiving medium P having received the transferred image isseparated from the photosensitive member surface and introduced to theimage fixing means 8 to have the image fixed and to be printed out ofthe machine as a duplicate (a copied material).

After the image transfer, the surface of the photosensitive member 1 iscleaned with a cleaning means 6 to remove the residual toner, and isrepeatedly used for image formation.

As the charging means 2 for uniformly charging the photosensitive member1 eleotrostatically, corona charging apparatus are generally and widelyused. As the transferring apparatus, corona transferring means are alsogenerally and widely used. Plural means from among the constitutionalelements, such as a photosensitive member, a developing means, and becleaning means, may be integrated into one apparatus unit, which may bemade freely mountable and dismountable. For example, the photosensitivemember 1 and the cleaning means 6 are integrated into one apparatus unitand are made to be freely mountable and dismountable by use of a guidemeans such as a rail provided in the body of the apparatus. Theapparatus unit may be constituted to incorporate a charging means and/ora developing means.

EXAMPLES 1-47

On an aluminum substrate plate, a subbing layer having a dried filmthickness of 1 μm has provided by applying with a Meyer bar a solutionof 5 g of a methoxymethylated nylon resin (number-average molecularweight: 32000) end 10 g of an alcohol-soluble copolymer nylon resin(number-average molecular weight: 29000) in 95 g of methanol.

Separately, 5 g of Compound A-1 shown before was added into a solutionof 2 g of a butyral resin (butyralation degree: 63 mole %) in 95 gcyclohexanone and was dispersed with a sand mill for 20 minutes. Thisdispersion was applied on the preliminarily formed subbing layer to givea dried thickness of 0.2 μm with a Meyer bar, to form acharge-generating layer.

5 g of the hydrazone compound represented the formula below: ##STR54##and 5 g of polymethyl methacrylate (number-average molecular weight:100000) were dissolved in 40 g of monochlorobenzene. The solution wasapplied on the charge-generating layer prepared above with a Meyer barand dried to form a charge-transporting layer having a thickness of 20μm, thus providing a photosensitive member of Example 1.

The photosensitive member of Examples 2 to 47 were prepared in the samemanner as described above except that compounds other than compound A-1,which are shown in Table 1, were employed.

The electrophotographic photosensitive members prepared thus wereevaluated for charging characteristics with an electrostatic copyingpaper tester (Model SP-428, made by Kawaguchi Denki K.K.), where thephotosensitive member was negatively charged by corona discharge of -5KV, left standing for 1 second in the dark, and exposed to light of 10lux with a halogen lamp. The evaluation of the charging characteristicswere performed by measuring the surface potentials (V_(O)) and theamounts of exposure (E_(1/2)) required for decreasing by half thesurface potential after left standing in the dark.

The results are shown in Table 1 and Table 2.

                  TABLE 1                                                         ______________________________________                                        Example  Compound                                                             No.      No.          V.sub.O (-V)                                                                           E1/2 (lux · sec)                      ______________________________________                                         1       A-1          700      3.2                                             2       A-2          680      3.6                                             3       A-3          695      2.5                                             4       A-4          705      2.6                                             5       A-5          680      4.1                                             6       A-6          690      3.8                                             7       A-7          695      3.2                                             8       A-8          700      2.6                                             9       A-9          710      2.6                                            10       A-10         700      6.9                                            11       A-11         695      4.5                                            12       A-12         680      5.1                                            13       A-13         705      3.8                                            14       A-14         695      3.6                                            15       A-15         710      3.0                                            16       A-16         715      2.8                                            17       A-17         710      2.4                                            18       A-18         700      3.8                                            19       A-19         710      3.1                                            20       A-20         695      4.3                                            ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Example  Compound                                                             No.      No.          V.sub.O (-V)                                                                           E1/2 (lux · sec)                      ______________________________________                                        21       B-1          695      4.1                                            22       B-2          710      2.1                                            23       B-3          705      3.2                                            24       B-4          715      2.8                                            25       B-5          700      2.6                                            26       B-6          700      2.0                                            27       B-7          690      3.2                                            28       B-8          685      4.7                                            29       B-9          700      3.8                                            30       B-10         675      5.0                                            31       B-11         680      4.9                                            32       B-12         690      5.9                                            33       B-13         700      3.7                                            34       B-14         695      4.8                                            35       B-15         705      3.4                                            36       B-16         710      2.9                                            37       B-17         705      2.6                                            38       B-18         690      4.0                                            39       B-19         695      5.9                                            40       B-20         705      3.6                                            41       B-21         710      2.8                                            42       B-22         715      2.9                                            43       B-23         700      3.1                                            44       B-24         695      3.7                                            45       B-25         700      2.0                                            46       B-26         705      7.2                                            47       B-27         705      2.9                                            ______________________________________                                    

EXAMPLES 48-53

The electrophotographic photosensitive members prepared in Examples 4,9, 17, 26, 37, and 45 were charged to -700 V, and the amounts of lightexposure (E_(1/2) : μJ/cm²) to reduce the potential by half weremeasured with the apparatus used in Example 1. The light source used wasan aluminum/pallium/arsine semiconductor laser (oscillation wavelength:780 nm). The results are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                        Example No.  Compound No.                                                                              E.sub.1/2  (μJ/cm.sup.2)                          ______________________________________                                        48           A-4         0.83                                                 49           A-9         0.85                                                 50           A-17        0.77                                                 51           B-6         0.68                                                 52           B-17        0.90                                                 53           B-25        0.71                                                 ______________________________________                                    

These results show that the electrophotographic photosensitive membersof the present invention have sufficient sensitivity also in thewavelength region of semiconductor laser oscillation.

EXAMPLES 54-56

The electrophotographic photosensitive member prepared in Example 3 wasattached to a cylinder of an electrophotographic copying machineequipped with a -6.5 KV corona charger, an optical exposing system,image developer, a transfer charger, a charge-eliminating opticalexposing system, and a cleaner.

The dark potential (V_(D)) and the light potential (V_(L)) at theinitial stage were set at about -300 V and -200 V, respectively. Afterrepeatedly used 5000 times, the dark potential and the light potentialwere measured.

The evaluation was also conducted in the same manner for thephotosensitive members prepared in Examples 22, and 45. The results areshown in Table 4.

                  TABLE 4                                                         ______________________________________                                                                       After 5000                                     Example                                                                              Compound  Initial       repetitions                                    No.    No.       V.sub.D (-V)                                                                           V.sub.L (-V)                                                                         V.sub.D (-V)                                                                         V.sub.L (-V)                          ______________________________________                                        54     A-3       700      195    690    205                                   55     B-2       705      200    685    215                                   56      B-25     700      200    685    210                                   ______________________________________                                    

EXAMPLE 57

On an aluminum surface of an aluminum-vapor-deposited polyethyleneterephthalate film, a subbing layer of polyvinyl alcohol having a filmthickness of 0.5 μm was formed. Thereon, the compound dispersionemployed in Example 3 was applied with a Meyer bar and dried to form &hecharge-generating layer of 0.2 μm thick.

The styryl compound (5 ) represented by the formula below: ##STR55## and5 g of a polycarbonate resin (number average molecular weight: 55000)were dissolved in 40 g of tetrahydrofuran. This solution was applied onthe charge-generating layer prepared above and dried to form acharge-transporting layer of 20 μm thick. The photosensitive member thusprepared was tested for charging characteristics and durability in thesame manner as in Example 1 and Example 52.

The results are shown below. The negative sign for the variation of thepotential (ΔV) means the decrease of the absolute value of thepotential, and the positive sign means the increase thereof.

    ______________________________________                                        V.sub.O  705 (-V)      E.sub.1/2                                                                             2.1 (lux · sec)                       ΔV.sub.D                                                                          10 (V)       ΔV.sub.L                                                                         10 (V)                                        ______________________________________                                    

EXAMPLE 58

A photosensitive member was prepared by applying the charge-generatinglayer and the charge-transporting layer of Example 57 in the reverseorder. The photosensitive member was evaluated for chargingcharacteristics in the same manner as in Example 1, provided that thecharging was made positive.

    ______________________________________                                        V.sub.O  690 (+V)      E.sub.1/2                                                                             3.5 (lux · sec)                       ______________________________________                                    

EXAMPLE 59

On the charge-generating layer prepared in Example 57, a solution of 5 gof 2,4,7-trinitro-9-fluorenone and 5 g ofpoly-4,4'-dioxydiphenyl-2,2'-propane carbonate (molecular weight:300000) in 50 g of tetrahydrofuran was applied with a Meyer bar anddried to form a charge-transporting layer of 18 μm thick.

The eIectrophotographic photosensitive member prepared thus wasevaluated for charging characteristics in the same manner as in Example1, provided that the charging was made positive.

    ______________________________________                                        V.sub.O  680 (+V)      E.sub.1/2                                                                             3.9 (lux · sec)                       ______________________________________                                    

EXAMPLE 60

Using a paint shaker, 0.5 g of the compound used in Example 3 was shakenwith 9.5 g of cyclohexanone for 5 hours to disperse the compound.Thereto a solution of 5 g of the charge-transporting material employedin Example 1 and 5 g of a polycarbonate resin in 40 g of tetrahydrofuranwas added, and the mixture was shaken for further 1 hour. The coatingliquid thus prepared was applied and dried on an aluminum substrateplate by means of a Meyer bar to form a photosensitive layer of 20 μmthick.

The electrophotographic photosensitive member prepared thus wasevaluated for charging characteristics in the same manner as in Example1 provided that the charging was made positive.

    ______________________________________                                        V.sub.O  690 (+V)      E.sub.1/2                                                                             4.6 (lux · sec)                       ______________________________________                                    

What is claimed is:
 1. An electrophotographic photosensitive member having a photosensitive layer on an electroconductive support, said photosensitive layer comprising a laminated structure of a charge-generating layer on the electroconductive support and a charge-transporting layer on the charge-generating layer, wherein said charge generating layer contains a dispersed compound having a structure represented by the general formula ( 1) or (2) as a charge-generating material: ##STR56## wherein A₁ and A₃ are respectively an aromatic radical or an aromatic heterocyclic radical; wherein when A₃ is an electron-accepting moiety, then A₁ is an electron-donating moiety and when A₃ is an electron-donating moiety, then A₁ is an electron-accepting moiety; A₂ is hydrogen atom and n is an integer of 1, 2, or
 3. 2. The electrophotographic photosensitive member of claim 1, wherein the aromatic radical is at least one selected from the group consisting of aromatic monocyclic radicals, aromatic condensed polycyclic radicals, assembled ring radicals constituted by direct combination of two or more of the aromatic monocyclic radicals and aromatic condensed polycyclic radicals, aromatic ketone radicals, sulfur derivatives of the aromatic ketone radicals, dicyanomethylene derivatives of the aromatic ketone radicals, aromatic quinone radicals, sulfur derivatives of the aromatic quinone radicals, and dicyanomethylene derivatives of aromatic quinone radicals.
 3. The electrophotographic photosensitive member of claim 1, wherein the heterocyclic ring radical is at least one selected from the group consisting of heterocyclic monocyclic ring radicals, condensed heterocyclic radicals constituted by condensation with a benzene ring or an aromatic condensed polycyclic group, and assembled ring radicaIs constituted by direct combination of two or more of the heterocyclic monocyclic radicais and condensed heterocyclic radicals, or by direct combination of at least one of the heterocyclic monocyclic radicals and condensed heterocyciic radicals and at least one of the aromatic monocyclic radicals and aromatic condensed polycyclic radicais.
 4. The electrophotographic photosensitive member of claim 1, wherein the electron-donating moiety is linked on the N side of the >C═N-- bond, and an electron-accepting moiety is bonded on the C side thereof in the general formulas (1) and (2).
 5. The electrophotographic photosensitive member of claim 1, wherein the electron-donating moiety is at least one selected from the group consisting of aromatic monocyclic radicals, aromatic condensed polycyclic radicals, and assembled ring radicals constituted by direct combination of two or more of the aromatic monocyclic radicals and aromatic condensed polycyclic radicals, which may have an electron-donating substituent; aromatic amine radicals which may have an electron-donating substituent; heterocyclic monocyciic radicals which may have an electron-donating substituent; condensed heterocyclic radicals constituted by condensing the heterocyclic radicals with a benzene ring or an aromatic condensed polycyclic group; and assembled ring radicals constituted by direct combination of one or two of the heterocyclic monocyclic groups or condensed heterocyclic groups.
 6. The electrophotographic photosensitive member of claim 5, wherein the electron-donating moiety is at least one selected from the group consisting of aromatic monocyclic radicals, aromatic condensed polycyclic radicals, and assembled ring radicals constituted by direct combination of two or more of the aromatic monocyclic radicals and aromatic condensed polycyclic radicals, which may have an electron donating substituent; aromatic amine radicals which may have an electron-donating substituent; heterocyclic monocyclic radicals which may have an electron-donating substituent; a condensed heterocyclic radicals constituted by condensing the heterocyclic radicals with a benzene ring or an aromatic condensed polycyclic group; and assembled ring radicals constituted by direct combination of one or two of the heterocyclic monocyclic groups and condensed heterocyclic groups.
 7. The electrophotographic photosensitive member of claim 5, wherein the electron-donating moiety is selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene, indene and fluorene which have an electron-donating substituent; pyrene which may have an electron-donating substituent; assembled ring radicals constituted by direct combination of two or more thereof; triphenylamine, diphenylamine, diphenylmethylamine which may have an electron-donating substituent: furan, thiophene, pyrrole, oxazole, thiazole, imidazole, pyridine, pyrazine, acridine, phenazine, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, benzoxazole, benzothiazole, thianthrene, phenoxazine, phenothiazine which have an electron-donating substituent; and indole, carbazole, iminodibenzyl, tetrathiafulvalene, dibenzotetrathiafulvalene which may have an electron-donating substituent; condensed heterocyclic radicals which are constituted by condensation of the heterocyclic ring with a benzene ring or an aromatic condensed polycyclic ring; end assembled ring radicals constituted by direct combination of two or more of the heterocyclic monocyclic radicals and the condensed heterocyclic groups.
 8. The electrophotographic photosensitive member of claim 1, wherein the electron-accepting moiety is at least one selected from the group consisting of aromatic monocyclic radicals, aromatic condensed polycyclic radicals, and assembled ring radicals constituted by direct combination of two or more of the monocyclic radicals and condensed polycyclic radicals which have an electron-accepting substituent; aromatic ketone radicals and dicyanomethylene derivative radicals thereof, aromatic thioketone radicals, and aromatic quinone radicals and dicyanomethylene derivative radicals thereof, which may have an electron-accepting substituent; heterocyclic monocyclic radicals, condensed heterocyclic radicals which are constituted by condensation with a benzene ring or an aromatic condensed polycyclic radical, which have an electron-accepting substituent; and assembled ring radicals constituted by direct combination of two or more of the heterocyclic monocyclic groups and condensed heterocyclic polycyclic groups.
 9. The electrophotographic photosensitive member of claim 8, wherein the electron-accepting moiety is at least one selected from the group of aromatic ketone radicals and dicyanomethylene derivative radicals thereof, aromatic thioketone radicals, and aromatic quinone radicals and dicyanomethylene derivative radicals thereof, which may have an electron-accepting substituent.
 10. The electrophotographic photosensitive member of claim 8, wherein the electron-accepting moiety is at least one selected from the group consisting of benzene, naphthalene, anthracene, phenanthrene, indene, and fluorene which have an electron-accepting substituent and assembled ring radicals constituted by direct combination of one or two of the monocyclic group and condensed polycyclic groups; benzophenone, fluorenone, and benzanthrone which may have an electron-accepting substituent, and dicyanomethylene derivative radicals thereof; benzoquinone, naphthoquinone, anthraquinone, and pyrenequinone, and dicyanomethylene derivative radicals thereof; furan, thiophene, pyrrole, oxazole, thiazole, imidazole, pyridine, pyrazine, acridine, phenazine, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, benzoxazole, benzothiazole, thianthrene, phenoxazine, and phenothiazine which have an electron-accepting substituent, and condensed heterocyclic radicals which are condensed with a benzene ring or an aromatic condensed polycyclic group and assembled ring radicals constituted by direct combination of two or more of the heterocyclic monocyclic groups and the condensed heterocyclic polycyclic groups.
 11. The electrophotographic photosensitive member of claim 1, wherein a subbing layer is provided between the electroconductive support and the photosensitive layer.
 12. The electrophotographic photosensitive member of claim 1, wherein a protective layer is provided on the photosensitive layer.
 13. An electrophotographic apparatus comprising an electrophotographic photosensitive member having a photosensitive layer on an electroconductive support, said photosensitive layer comprising a laminated structure of a charge-generating layer on the electroconductive support and a charge-transporting layer on the charge-generating layer, wherein said charge generating layer contains a dispersed compound having a structure represented by the general formula (1) or (2) as a charge-generating material.wherein A₁ and A₃ are respectively an aromatic radical or an aromatic heterocyclic radical; wherein when A₃ is an electron accepting moiety, then A₁ is an electron donating moiety and when A₃ is an electron donating moiety, then A₁ is an electron accepting moiety; A₂ is hydrogen atom and n is an integer of 1, 2, or
 3. 